1. Field of the Invention
The present invention relates to a data transmission apparatus, a data reception apparatus, a data transmission method, a data reception method, a data transmission and reception system, a data transmission program, a data reception program, and a data transmission and reception program which can send information having a large amount of data such as image information by reducing the data amount or can receive the information such that the information can be restored.
2. Description of the Related Art
Conventionally, there has been known a technique with which, when data is sent and received between two computer terminals, a transmission side compresses data to be sent (reduces a data amount such that data can be restored) and sends the data, and a reception side restores the compressed data to its original state (data expansion). According to the technique of data compression, an amount of data to be sent and received can be reduced, whereby communication costs can be held down low and, at the same time, it is easily made possible to handle multimedia data having a large amount of data such as still image data and moving image data with a general personal computer.
As a method of data compression, for example, the JPEG (compression standards for color still images) for still images, the MPEG (compression standards for color moving images) for moving images, and the like are well known.
The JPEG for still images and the MPEG for moving images realize reduction in a data amount by curtailing image data in a degree unnoticeable for human eyes.
On the other hand, as a method of sending and receiving a large capacity of data such as a still image or a moving image without using the compression technique, there is known a method of installing a leased line as it is often used in printing industries or the like. Deterioration of data can be prevented and transmission and reception of data can be performed at a high speed when the leased line is used.
Since the still image data compression method such as the JPEG for still images realizes reduction in a data amount by curtailing data as described above, deterioration of data becomes conspicuous when a degree of compression is increased. Therefore, it is difficult to realize significant reduction in a transmission data amount only through the compression technique.
In addition, although the method of installing a leased line for sending and receiving a large amount of data can send and receive a large amount of data while suppressing deterioration of data, costs for arranging the infrastructure of leased line installation become extremely high.